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Title: Collisionless tearing instability in a non-Maxwellian neutral sheet: An integrodifferential formulation

Journal Article · · Phys. Fluids; (United States)
DOI:https://doi.org/10.1063/1.865395· OSTI ID:5646841

An integro-differential formalism is developed to study the collisionless tearing instability in a non-Maxwellian neutral sheet. The exact unperturbed particle orbits are used analytically in the orbit integrals. The treatment is linear, self-consistent, and kinetic for both ions and electrons. The analysis is carried out for low-frequency, purely growing electromagnetic perturbations (Vertical Bar..omega..Vertical Bar<<..omega../sub c/i). Using the Galerkin method, the integro-differential equation is solved to obtain the dispersion relation and the eigenmode structure. A sufficient condition for instability is given on the basis of a quadratic form and the eigenvalues of a self-adjoint integro-differential operator. The formalism is applied to a specific model distribution. For the case where the electrons and ions are both non-Maxwellian, it is found that the instability is dominated by the axis-crossing electrons and that the eigenmode is strongly localized to a region of the order of ( rho/sub e/z/sub p/)/sup 1//sup ///sup 2/ at the null plane, where rho/sub e/ is a measure of the electron gyroradius in the asymptotic magnetic field and z/sub p/ is the sheet thickness. It is shown that the growth rate can be enhanced by several orders of magnitude over the isotropic case and that short wavelength perturbations are strongly preferred. The dispersion relation has the general form ..gamma../kv/sub e/parallel = const where kparallelB/sub 0/ and v/sub e/parallel is the electron thermal velocity along B/sub 0/, the equilibrium magnetic field.

Research Organization:
Science Applications International Corporation, 1710 Goodridge Drive, McLean, Virginia 22102
OSTI ID:
5646841
Journal Information:
Phys. Fluids; (United States), Vol. 28:7
Country of Publication:
United States
Language:
English